[ubiquitousbhoy]

Hi guys,

I believe this is a simple question to answer, but it has bugged me for a while! It is to do with using moles of catalyst per functional group.

I have a pre-polymer that contains approximately four reactive functional groups per polymer chain with MW of around 1700

10g of my pre-polymer = 0.0058 moles approx.

my question is do I divide the moles of pre-polymer by 4 to give the number of moles per functional group? or multiply by 4?

Thanks in advance for any replys!

[typhoon2028]

If each reative site requires one molecule of catalyst, would not the following be true?

1 mole Pre-Polymer + 4 moles of Catalyst = 1 mole of Product

What polymer system are you working with?

[ubiquitousbhoy]

Hi Typhoon,

What you have written seems to make sense. So in effect, I'd multiply the number of moles by four and this represents the number of moles of reactive functional groups. Which would react with a multi-functional cross linker of my choosing.

I am working with polyurethane pre-polymers that are further functionalised.

Thanks for reply.

[hafan]

If each reative site requires one molecule of catalyst, would not the following be true?

1 mole Pre-Polymer + 4 moles of Catalyst = 1 mole of Product

What polymer system are you working with?

[typhoon2028]

What I wrote was very simple. 

To be safe I would start with less catalyst, because your reaction may give off heat.  This may further accelerate the reaction and make it difficult to control.

I have worked with polyureathane foam before.  I have made pre-polymer of TDI and polyol.  The reaction must be monitored, as the viscosity changes and heat can build.